Shiite Muslims gathered on the streets of London Wednesday to mark a year since Saudi Arabia executed 47 enemies of the state. Those killed included the prominent Shiite cleric Sheikh Nimr al-Nimr.

Al-Nimr was considered a terrorist by the state thanks to his role as a central figure in the 2011 Arab Spring anti-government protests, and is said to have a strong following among young Saudi Shias living in the Sunni majority country.

His execution sparked riots in Tehran and a diplomatic crisis between Saudi Arabia, Sudan, Bahrain, and Iran.

The protest isn’t the first time that Islamic sectarian politics have played out on the streets of Britain.

In March 2015 Kurds, celebrating the traditional Iranian New Year celebrations, clashed with Islamists on the streets of London. Footage filmed by a group of local youths showed dozens of men swinging bats and throwing bricks at each other while police in high visibility jackets try to separate them.

The following year, some British Muslims cheered the death of a British Ahmadiyyah Muslim, Asad Shah, at the hands of a British Sunni Muslim, Tanveer Ahmed. Ahmed said he had been moved to kill Mr. Shah because he believed him to be an apostate.